Interestingly, we found that TRIM26, SOCS2, and ZRANB1, three E3s reported to regulate SLC7A11 in liver cancer cell lines (30), mouse liver (31), or kidney renal clear cell carcinoma (32), and OTUB1 and DUBA, two DUBs, reported to regulate SLC7A11 in few types of human cancer cell lines (22) or differentiated cancer stem cells (33), respectively, were not subjected to cystine regulation in breast cancer cells (Fig. 5 A–C and SI Appendix, Fig. S6 C–E). This evidence concerns the gene OTUB1 and liver cancer.